Migration Manager provides tools for seamless migration to Microsoft Office 365 from on-premises Exchange environment.
We assume that you are familiar with Migration Manager concepts described in the Migration Manager Installation Guide, and that you have already installed the product, following the instructions provided in that guide. It is also recommended that you read the release notes for the current version of Migration Manager. The release notes contain information about specific product behavior, limitations, known issues, and workarounds that may be useful for planning and performing your migration.
For information which types of source Exchange environments are supported, see Cloud Migration subsection of Source and Target Exchange Organizations.
Migration Process Overview
Migration Manager supports various scenarios of migrating your messaging infrastructure to Microsoft Office 365. This topic describes a basic migration when messaging infrastructure is completely moved to Microsoft Office 365.
Note: Migration Manager supports various cloud migration scenarios that involves hybrid deployments. For detailed information how to implement them, see Hybrid Migration Scenarios.
The basic migration to Microsoft Office 365 consists of the following main stages:
- Preparing on-premises Exchange and Microsoft Office 365 environments for migration.
- Synchronizing entire Active Directory with Microsoft Office 365 to provide for co-existence of Global Address List and to provision users in Microsoft Office 365.
- Synchronizing calendars including free/busy information to Microsoft Exchange Online.
- Synchronizing public folders with Microsoft Office 365.
- Migrating and switching mailboxes to Microsoft Office 365.
- Re-migrating some Active Directory objects to set specific settings for them (optional).
- Performing post migration activities like redirecting email, updating Outlook profiles, etc.
TIP: If you plan to implement Single Sign-On (SSO) for Microsoft Office 365, or you already use Microsoft Azure AD Connect to synchronize user accounts with Microsoft Office 365, review information in the Advanced Migration Topics section.
The table below describes the steps that you need to perform in each stage of migration and the results that you get after you complete those steps.
Exchange Resource Forest Migration Considerations
If your Exchange organization is deployed in an Exchange resource forest then consider the following:
- You should provision users directly from Exchange resource forest instead of the corresponding Active Directory authentication forest.
- Despite all user accounts in the Exchange resource forest are disabled by default, Migration Manager for Active Directory creates them enabled in Microsoft Office 365.
- After you provision users, you may start synchronizing calendars and migrating mailboxes from the Exchange resource to Microsoft Office 365 forest using Migration Manager for Exchange.
- If you need to migrate specific attributes that are presented only in the corresponding Active Directory authentication forest, you can do so by creating a separate migration pair of that authentication forest and Microsoft Office 365 in Migration Manager for Active Directory (Microsoft Office 365).
Mailbox Permissions Processing Considerations
Migration Manager can synchronize mailbox permissions and the Send As permission during synchronization and migration to Microsoft Office 365. So if a source user can send mail messages as another user account and/or manage mailboxes of other users, the corresponding target user will have the same rights.
Take into account the following:
- The Rollback Task cannot revert changes of the Send As and mailbox permissions that were made during migration or synchronization.
- If any of these permissions is removed on the source, this action will not be synchronized on the target during the next migration or synchronization session.
- If a source user has the Deny Send As permission, the corresponding target user will have no Send As permission (neither Allow nor Deny) after synchronization. If the user has the Allow Send As permission for any mailbox on the source and a membership in a group that has the Deny Send As permission for the same mailbox, this user will have the Allow Send As permission on the target.
- The Send As permissions are synchronized only for mailboxes. If a user has the Send As permission for a group (i.e. is able to send emails from this group), the corresponding target user will not have this permission.
- This functionality is not supported in the Exchange resource forest when permissions are granted to users or groups from the account forest.
Mail Redirection Technology Overview
For uninterrupted user collaboration during the migration to Microsoft Office 365, users in source Exchange organization and Microsoft Office 365 should see other users’ mailboxes in their Global Address Lists (GALs). All mail sent to the user should arrive to the mailbox he or she is currently using, no matter which mailbox it was sent to. To achieve this, mail should be automatically forwarded to the currently-used mailbox from the other mailbox. For that, Migration Manager establishes mail redirection between source Exchange servers and Microsoft Office 365 using the Migration Manager for Active Directory redirection technology as follows:
- Before a mailbox switch, all new mail is delivered to the source user mailbox and redirection is configured for the corresponding cloud user mailbox.
- After the mailbox switch, all new mail is delivered to the cloud mailbox, redirection on the cloud mailbox is disabled, and redirection is configured for the source mailbox
The process of mail redirection is fully automated by Migration Manager for Active Directory; therefore no additional configuration activities are required to be performed.
Before you start the migration, read the following:
Recommendation: Subscribe to Microsoft Office 365 in Advance
If you do not already have a Microsoft Office 365 account, consider signing up at http://office.microsoft.com before you start migration preparations. This will help avoid delays and interruptions during migration.